Various types of filters are known in the marketplace and in the patent literature.
Back-flushable filters of various types are well known in the art for a great variety of applications. A particularly successful type of backflushable filter employing filter disks is described and claimed in the following patents of applicant: U.S. Pat. Nos. 4,026,806; 4,042,504; 4,045,345; 4,271,018; 4,295,963.